<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>difference</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const difference = (a, b) => {
            const s = new Set(b);
            return a.filter(x => !s.has(x));
        };
        console.log(difference([1, 2, 3, 3], [1, 2, 4]));
    </script>
</body>

</html>